BMSCs and Pectin-Based E2-Loaded Microcapsules with Injectable Pectin-Pluronic® F-127 Scaffolds for Mouse Endometrial Regeneration Application

Abstract: Background Uterine endometrium is a highly dynamic tissue which consists of a basal layer and a functional layer. Bone marrow-derived mesenchymal stem cells (BMSCs) have been recognized as new candidates for the treatment of serious endometrial injuries. However, due to the local microenvironment of damaged endometrium, transplantation of BMSCs yielded disappointing results with respect to survival, attachment, differentiation, and proliferation. Methods Pectin-Pluronic® F-127 scaffolds were fabricated. E2 was encapsulated into the W/O/W microspheres to construct pectin-based E2-loaded microcapsules (E2 MPs). The BMSCs/E2 MPs/scaffolds system was then injected into the uterine cavity of mouse endometrial injury model. Furthermore, the mechanism of E2 in promoting the repair of endometrial injury was also investigated. Result Pectin-Pluronic® F-127 scaffolds could provide three-dimensional architecture for the attachment, growth, and migration of BMSCs. E2 MPs has the potential to serve as a long-term reliable source of E2 for endometrial regeneration. At four weeks after transplantation, it was demonstrated that the system increased proliferative abilities of uterine endometrial cells, facilitated microvasculature regeneration, and restored the ability of endometrium to receive an embryo, suggesting that the BMSCs/E2 MPs/scaffolds system is a promising treatment option for endometrial regeneration. Exosomes are critical paracrine mediators that act as biochemical cues to direct stem cell differentiation. In this study, it was found that the expression of endometrial epithelial cells (EECs) markers was up-regulated in BMSCs treated by exosomes secreted from endometrial stromal cells (ESCs-Exos). Exosomes derived from E2-stimulated ESCs further promoted the expression level of EECs markers in BMSCs, suggesting exosomes released from ESCs by E2 stimulation could enhance the differentiation efficiency of BMSCs. Conclusion The BMSCs/E2 MPs/scaffolds therapeutic strategy may be beneficial in the treatment of severely damaged endometrium. Exosomes derived from ESCs play paracrine roles in endometrial regeneration stimulated by E2, potentially modulating the differentiation of BMSCs.